Mercedes SL Oxygen Sensor Issue

I had a similar issue with my old Subaru Impreza. Check engine light and poor fuel efficiency can often point to the exhaust sensor failing. Could be a defective automotive sensor or even just a loose connection. It’s worth checking the easy stuff first before assuming the worst.

Thanks for the quick reply! When you say 'easy stuff,' are we talking about just visually inspecting the connections? Is there anything I can test with a multimeter before I take it in?

Yeah, visually inspect the connections for corrosion or damage. On the Subaru, the plug connection was the problem. I didn't measure anything, I simply pushed them together. If visual inspection yields nothing, I would get it properly diagnosed to confirm which oxygen sensor is failing. The repair will be about 95€ if this is the case.

Appreciate the advice! Ended up taking it to a shop and you were spot on – turned out to be a faulty connection on the oxygen sensor. They cleaned it up and the check engine light is gone and MPG is back to normal. Thanks again!